1. Field of the Invention
The present invention relates to a device to prevent erroneous handling of a camera having an automatic exposure determination device as can be applied to either an automatic diaphragm system with shutter time preference (EE) or an automatic shutter speed determination system with diaphragm preference (auto).
2. Description of the Prior Art
Systems to automatically control exposure of a camera, include shutter time preference means to set shutter time beforehand for automatically controlling the diaphragm, and diaphragm preference means to set the diaphragm aperture beforehand for automatically controlling shutter time. However, while proper shutter time can be selected for a moving object by the shutter time preference, depth of photographing field can not be set freely. On the other hand, while proper the depth for photographing an object can be selected for a stationary object by setting of the appropriate diaphragm aperture as desired, shutter time can not be set freely in the diaphragm preference. Since both shutter time preference and diaphragm preference have respective advantages and disadvantages, a dual preference camera having both the functions of the shutter preference and the diaphragm preference both has been proposed. Such a dual preference camera may have a dial etc., to set shutter time, a change over member to switch the shutter time to be automatically controlled, a ring, etc. to set the diaphragm, and a change over member to so change over the diaphragm to automatic control. In shutter time preference photography, when any desired shutter time is set and the diaphragm is so controlled as to be automatically controlled, when shutter release is effected exposure can be accomplished such that the diaphragm aperture is automatically controlled based on the brightness of an object. Also in diaphragm preference photography, when any desired diaphragm aperture is set and shutter time is so changed as to enable automatic control then shutter release is effected, such exposure can be accomplished such that shutter time is automatically controlled based on the brightness of an object. But the camera has the shortcoming that when shutter release is effected by so changing shutter time as to make it automatically controlled and at the same time so changing over the diaphragm as to make it automatically controlled also, determination of such shutter time and diaphragm aperture as will provide proper exposure can not be accomplished, resulting in failure in photographing.